Analysis of mechanical and structural properties of micro alloyed steel welded joints depending on quality of cored wire

Abstract

The aim of this study was to master new quality cored wires made of steel strips and the cores filled with metal powders and low molecular hydrophobic compounds. For experimental research, the specimens were made of micro alloyed steel type NIOMOL 490K intended for making welded structures subjected to dynamic loads and effects of low temperature. Welding of test specimens was done using the MAG method in CO2 shielding with two new quality cored wires. The testing included the determination of mechanical properties of the base metal (BM) and the weld metal (WM), which apart from having sufficient strength must also have good toughness. The microstructures of BM, WM and heat affected zone (HAZ) were analysed, due to possible formation of a heterogeneous microstructure, which can reduce toughness. Results of testing of welded joints should define a new quality of cored wires in view of welding-technological characteristics. The results indicate that the new quality cored wires can produce good mechanical-structural properties of welded joints.